<!DOCTYPE html>
<html lang="ch">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    
</body>
</html>
<script>
    //判断是否为七的平方的倍数
    var num=prompt("请输入一个数字");
    if(num%49==0){
        console.log("是");
    }else if(num%49!=0){
        console.log("不是七的倍数")
    }
</script>